Your reality is out of date MAR 18 2010
There's a category of information that slowly changes throughout the course of a lifetime. Sam Arbesman calls them mesofacts.
These are facts which we tend to view as fixed, but which shift over the course of a lifetime. For example: What is Earth's population? I remember learning 6 billion, and some of you might even have learned 5 billion. Well, it turns out it's about 6.8 billion. [...] If, as a baby boomer, you learned high school chemistry in 1970, and then, as we all are apt to do, did not take care to brush up on your chemistry periodically, you would not realize that there are 12 new elements in the Periodic Table. Over a tenth of the elements have been discovered since you graduated high school!
The blog over at mesofacts.org is a good place to update yourself on this slowly changing information.